Electrodeposition of nickel



United States Patent 3,378,470 ELECTRODEPOSITION 0F NICKEL Harry Kroll, Warwick, R.I., assignor, by mesne assignments, to John S. Guleserian, Warwick, RI. No Drawing. Filed May 17, 1965, Ser. No. 456,531 13 Claims. (Cl. 204-49) ABSTRACT OF THE DISCLOSURE Bright nickel plating baths comprising aqueous nickel salt solution containing an ester reaction product of maleic acid and acetylenic alcohol as a brightener.

This invention relates to compounds useful as additives to nickel electroplating baths and more particularly to the electrodeposition of smooth, lustrous deposits of nickel from baths containing these additives.

Background of the invention Brighteners are added to nickel plating baths, including the commonly used Watts-type acid bath, to increase the leveling characteristics and to produce bright nickel electrodeposits. The use of unsaturated molecules containing alkyne groups has been suggested. While compounds such as 1,4-butyne-diol and l,4 bis(hydroxyethoxy)butyne produce some degree of improvement in the plating bath, uniform results are difiicult to achieve. These deficiencies are readily evident in plating baths operated at temperatures above 50 C. Under these conditions, acetylenic alcoholic brighteners produce a cloudy haze on the nickel deposit which is most evident in those areas at which nickel is deposited under conditions of low current density. Many commercial products have complex shapes which dictate that the nickel is deposited in certain areas of the product at low current density. Accordingly, there exists a need for nickel plating baths in which irregularly shaped objects may be nickel electroplated with a uniform lustrous and bright nickel deposit. Such desirable electrodeposits must be made in the recesses of the object as well as in the elevated areas.

It is an object of this invention to provide a process for producing smooth lustrous electrodeposits of nickel.

It is also an object of this invention to provide superior baths for electrodepositing smooth lustrous nickel deposits.

The invention also contemplates providing compounds useful as brightener additives in nickel plating baths.

Other objects and advantages of this invention will in part be apparent, and will in part appear hereinafter.

Detailed description of the invention *The desired acetylenic-olefinic esters are prepared by reacting maleic acid with acetylenic alcohols and diols having the formula wherein R is hydrogen, H C- or HO(CH CH O),,CH and n is 0, l, or 2; and n must be 0 when R is hydrogen or methyl. Illustrative of these acetylenic alcohols and diols are propargyl alcohol; 1-hydroxy-butyne-2,3; 1,4-

3,378,470 Patented Apr. 16, 1968 "ice butynediol; and bis(hydroxyethoxy)1,4-butyne and higher ethylene oxide adducts of 1,4-butynediol. The olefinic dicarboxylic acid reactant in the preparation of the acetylenic-olefinic esters is maleic acid or such equivalent olefinic acid compounds as maleic anhydride, and the alpha, beta-olefinic dicarboxylic acids containing up to about 8 carbon atoms in the chain.

The composition of the acetylenic-olefinic esters is dependent upon the specific acetylenic compound and acid utilized and the relative proportions of each, and also is influenced by the reaction conditions. The products of the reaction may be mixtures of esters as will be apparent. The products of the reaction of maleic acid and an acetylenic mono-alcohol will be a monomeric ester which may be (i) a monoester formed by esterification of only one of the acid groups of the maleic acid by one molecule of the alcohol, or, (ii) a diester formed by esterification of both of the acid groups of the maleic acid by two molecules of the alcohol. Reaction of an acetylenic diol and the dicarboxylic acid may result in a variety of reaction products of a monomeric and polymeric nature. The reaction products may be mixtures of several of these polyesters. The reaction conditions utilized vary somewhat dependent upon the acetylenic alcohol reactant. Where it is a liquid and used in excess, it is often useful to dissolve the maleic acid in the alcohol and heat to temperatures up to about C., where such temperature is not above the temperature at which the reactants volatilize under the reaction conditions. It is often desirable to carry the reaction out in a solvent which is inert to the reactants and reaction products. Such reactions are preferably carried' out under reflex conditions. Maleic anhydride is often the preferred acid reactant instead of maleic acid. When used herein, it is understood that terms are used alternatively referring to these compounds which are equivalents for purposes of this invention. The following compounds are illustrative of these acetylenic-olefinic esters. Ester No:

(1) CH CECCH OC(O)CH=CHC(O)OH (2) HOCH CECCH OC(O)CH=CHC(O)OH (3) HOCH CH OCH C ECCHZOCHZCHZOC(O)CH=CHC(O)0H (4) CH CECCH OC(0)CH =CHC (O) OCH2CECCH3 (5) HOCH CECCH OC(O)CH =CHC O) OCH CECCH OH HO CH2CH2O CHzCEC CHzO CHzCHaO C O I H A...

HOCHzCHrO CHaCEC CHaO GHzCHzO (g 0 (7) HO(O)CCH=CHC(O)OCH C ECCHZOC (O CHiI-IC (O OH (8) HO O CCH=CHC O) OCH CH OCH C ECCHQOCHZC'HZOC O CH=CHC (O OH (9) HCECCH2OC(O)CHECHC(O)OH (l0) HCECCH2OC(O)CHZCHC(O) OCHZCECH ture range is between about 35 C. and 70 C. The concentration of the acetylenic-olefinic ester in the bath is between 0.001 and 1.0 gram/liter (g./l.), and preferably between 0.04 and 0.1 g./ l.

The acetylenic-olefinic esters are commonly used with auxiliary brighteners such as the aromatic and aliphatic unsaturated sulfonic acids, sulfonamides, and sulfonimides. They may, however, be employed as a brightening additive in electroplating baths which do not contain other additives. In addition to the baths discussed hereinbefore which contain nickel sulfate and/or nickel chloride, the acetylenioolefinic esters may also be employed in nickel plating baths containing the sulfamate anion.

The acetylenic-olefinic esters are most commonly used in conjunction with the following sulfonimides and sulfonamides: benzene sulfonamide; ortho-toluene sulfonamide; para-toluene sulfonnmide; Saccharin, sodium salt; metabenzene disulfonamide; allylsulfonamide; and vinyl benzenesulfonamide. Other sulphur compounds which may be incorporated in the baths are benzenesulfonic acid; allyl sulfonic acid; para-vinylbenzene sulfonic acid; 1,5- naphthalene sulfonic acid; and 1,3,6-naphthalene sulfonic acid. These compounds may be added as the specified compound per se and used in amounts between about 0.1 and 15 g./l. Those compounds containing salt-forming groups may be added in the form of their nickel, sodium, potassium, or magnesium salt.

The following are specific examples of aqueous acidic nickel elcctro-plating baths containing the acetylenic-olefinic esters. Bright, lustrous nickel electrodeposits are obtained over a wide current density range from these baths. The acetylenic-olefinic esters are identified by the Ester No. specified hereinbefore.

Example 1:

NiSO .6H O 300 NiCl .6H O 45 Boric acid 45 Saccharin 1 Brornobenzene sulfonic acid 1 Ester No. 3 0.08 Sodium lauryl oxyethyl sulfate 1.0 Temperature, C. 60 pH, 4.0.

Example 2:

NiSO .6H O 200 NiCl .6H O 100 Boric acid 45 Naphthalene trisulf-onic acid 5 Ester No. 8 0.10 Temperature, C. 60 pH, 4.0.

Example 3:

NiSO .6H O 300 NiCl .6l-I O 45 Boric acid 45 Saccharin 1 Toluenesulfonamide 0.5 Ester No. 2 0.05 Sodium lauryl sulfate 9.50 Temperature, C. 50-55 pH, 3.5-4.5.

Example 4:

- NiSO .6H O 250 NiCl .6H O 75 Saccharin 1.0 Vinyl benzenesulfonic acid 1.0 Ester No. 5 0.05 Sodium octyl sulfate 0.5 Temperature, C. 45

Temperature, C. a pH, 4.0.

Allyl-Z-vinylpyridinium bromide may be used in these baths in amounts between 0.01 and 1.0 g./l.

The aqueous acidic nickel electroplating baths containing the acetylenic-olefinic esters exhibit the unique property of producing nickel electrodeposits of high and uniform luster in areas of both high and low current density. This is attributed to the effects of these esters as additives. These esters were found to be more effective in this respect than the acetylenic alcohols or diols from which they are derived. It is critical that the esters contain both the acetylenic and the olefinic unsaturation. Esters which have been prepared by condensing the acetylenic alcohols and diols with citric acid, succinic acid, phthalic acid, and malic acid have been tested as brightener additives in Watts-type nickel plating bath. These esters had no brightening or leveling effect on the nickel deposit. In a number of instances, the baths containing these esters produced an inferior nickel plate.

Although this invention has been illustrated by reference to specific examples, numerous changes and modifications thereof which clearly fall within the scope of the invention will be apparent to those skilled in the art.

What is claimed is:

1. A bath for producing bright nickel electrodeposits comprising an aqueous acid solution of a nickel salt and between about 0.001 and 1 g./l. of an ester reaction product of maleic acid and an acetylenic alcohol having the formula wherein R is selected from the group consisting of hydrogen, H C-, and HO(CH CH O),,CH n is 0-2, and n is 0 when R is hydrogen or H C.

2. The nickel plating bath of claim 1 containing between about 0.1 and 15 g./l. of at least one organic sulphur compound selected from the group consisting of aromatic and aliphatic unsaturated sulfonic acids, aromatic sulfonamides, and sulfonimides.

3. The bath of claim 2 containing the ester reaction product of one mole of 1,4-bis(hydroxyethoxy)butyne with one mole of maleic acid.

4. The bath of claim 3 containing between 0.01 and 1.0 g./l. of allyl-2-vinylpyridinium bromide.

5. The bath of claim 2 containing the ester reaction product of one mole of 1,4-bis(hydroxyethoxy)butyne with two moles of maleic acid.

6. The bath of claim 2 containing the ester reaction product of one mole of 1,4-butynediol with two moles of maleic acid.

7. The bath of claim 1 containing between about 0.4 and 0.1 g./l. of said ester.

8. The bath of claim 1 wherein said ester is the reaction product of one mole of propargyl alcohol with one mole of maleic acid.

9. The bath of claim 1 wherein said ester is the reaction product of one mole of 1,4-butynediol and with one mole of maleic acid.

10. The bath of claim 1 wherein said ester is the reaction product of one mole of 1,4-bis(hydroxyethoxy)butyne with one mole of maleic acid.

11. The bath of claim 1 wherein said ester is the reaction product of one mole of 1,4-butynediol with 2 moles of maleic acid.

12. The bath of claim 1 wherein said ester is the reaction product of one mole of 1,4-bis(hydroxyeth0xy)butyne with 2 moles of 'maleic acid.

13. The process of electrodepositing bright nickel which comprises electrolyzing an aqueous acidic solution comprising a nickel salt and between about 0.001 and 1 g./l. of an ester reaction product of maleic acid and an acetylenic alcohol having the formula RCECC(H2) (OCH CH OH wherein R is selected from the group consisting of hydrogen, H C--, and HO(CH CH O) CI-I n is 0-2, and n is 0 when R is hydrogen or H C.

References Cited UNITED STATES PATENTS 2,959,553 11/1960 Rowlands et a1. 260485 XR 2,979,538 4/1961 Wotiz 260485 XR 3,306,831 2/1967 Cope 20449 XR 3,320,315 5/1967 Towle et a1. 20449 XR HOWARD S. WILLIAMS, Primary Examiner. G. KAPLAN, Assistant Examiner. 

